<?php

require_once 'HTMLPurifier/DefinitionCache.php';
require_once 'HTMLPurifier/DefinitionCache/Serializer.php';

HTMLPurifier_ConfigSchema::define(
	'Cache', 'DefinitionImpl', 'Serializer', 'string/null', '
This directive defines which method to use when caching definitions,
the complex data-type that makes HTML Purifier tick. Set to null
to disable caching (not recommended, as you will see a definite
performance degradation). This directive has been available since 2.0.0.
');

HTMLPurifier_ConfigSchema::defineAlias(
	'Core', 'DefinitionCache',
	'Cache', 'DefinitionImpl'
);


/**
 * Responsible for creating definition caches.
 */
class HTMLPurifier_DefinitionCacheFactory
{
	
	var $caches = array('Serializer' => array());
	var $implementations = array();
	var $decorators = array();
	
	/**
	 * Initialize default decorators
	 */
	function setup() {
		$this->addDecorator('Cleanup');
	}
	
	/**
	 * Retrieves an instance of global definition cache factory.
	 * @static
	 */
	function &instance($prototype = null) {
		static $instance;
		if ($prototype !== null) {
			$instance = $prototype;
		} elseif ($instance === null || $prototype === true) {
			$instance = new HTMLPurifier_DefinitionCacheFactory();
			$instance->setup();
		}
		return $instance;
	}
	
	/**
	 * Registers a new definition cache object
	 * @param $short Short name of cache object, for reference
	 * @param $long Full class name of cache object, for construction 
	 */
	function register($short, $long) {
		$this->implementations[$short] = $long;
	}
	
	/**
	 * Factory method that creates a cache object based on configuration
	 * @param $name Name of definitions handled by cache
	 * @param $config Instance of HTMLPurifier_Config
	 */
	function &create($type, $config) {
		$method = $config->get('Cache', 'DefinitionImpl');
		if ($method === null) {
			$null = new HTMLPurifier_DefinitionCache_Null($type);
			return $null;
		}
		if (!empty($this->caches[$method][$type])) {
			return $this->caches[$method][$type];
		}
		if (
		  isset($this->implementations[$method]) &&
		  class_exists($class = $this->implementations[$method])
		) {
			$cache = new $class($type);
		} else {
			if ($method != 'Serializer') {
				trigger_error("Unrecognized DefinitionCache $method, using Serializer instead", E_USER_WARNING);
			}
			$cache = new HTMLPurifier_DefinitionCache_Serializer($type);
		}
		foreach ($this->decorators as $decorator) {
			$new_cache = $decorator->decorate($cache);
			// prevent infinite recursion in PHP 4
			unset($cache);
			$cache = $new_cache;
		}
		$this->caches[$method][$type] = $cache;
		return $this->caches[$method][$type];
	}
	
	/**
	 * Registers a decorator to add to all new cache objects
	 * @param 
	 */
	function addDecorator($decorator) {
		if (is_string($decorator)) {
			$class = "HTMLPurifier_DefinitionCache_Decorator_$decorator";
			$decorator = new $class;
		}
		$this->decorators[$decorator->name] = $decorator;
	}
	
}

